Gardner’s syndrome is a rare genetic disorder. It usually causes benign or non-cancerous growths. It is classified as a subtype of familial adenomatous polyposis, which causes colon cancer.
Gardner syndrome is a variant of the disease ‘familial adenomatous polyposis’ (FAP), an inherited disease that is characterised by gastrointestinal polyps, multiple osteomas (benign bone tumours), and skin and soft tissue tumours. Polyps tend to form at puberty with the average age of diagnosis around 25 years of age.
In almost all patients, polyps will progress to malignancy, resulting in colorectal cancer so that timely detection is essential.
Gardner Syndrome is inherited as an autosomal dominant trait, so that an affected person has a 50% chance of passing on the gene to each of their children.
Gardner’s syndrome can lead to growths on various areas of the body. Tumors are most commonly found in the colon, sometimes in large numbers.
In addition to polyps on the colon, growths can develop, including fibromas, desmoid tumors, and sebaceous cysts, which are fluid-filled growths under the skin.
The condition is considered rare. It occurs in about one in 8,000 people.
What Causes Gardner’s Syndrome?
The syndrome is a genetic condition, which means it is inherited. The adenomatous polyposis coli (APC) gene produces APP protein. APC protein regulates cell growth and prevents cells from dividing too fast. People with Gardner’s syndrome have a defect in the APC gene.
This affects cell growth, which leads to abnormal tissue growth. What causes the mutation of the gene has not been determined.
What are the clinical features of Gardner syndrome?
Clinical features of Gardner syndrome can be divided into two types, cutaneous and non-cutaneous. The most noticeable cutaneous feature of Gardner syndrome is the appearance of epidermoid cysts.
These cysts can be differentiated from ordinary epidermoid cysts by the following factors:
- Epidermoid cysts of Gardner syndrome occur at an earlier age (around puberty) than ordinary cysts
- Epidermoid cysts occur in less common locations such as the face, scalp and extremities compared to ordinary cysts
- Cysts tend to be multiple in over half of the patients with Gardner syndrome
As with ordinary epidermoid cysts, cysts in Gardner syndrome are usually asymptomatic (without symptoms), however in some cases they may be pruritic (itchy) and/or inflamed, and they may rupture.
Other cutaneous features include fibromas, lipomas, leiomyomas, neurofibromas and pigmented skin lesions.
Non-cutaneous features include:
- Gastrointestinal polyps that nearly always transform into colonic adenocarcinomas (colon cancer).
- Osteomas – these benign bone tumours are essential in making the diagnosis of Gardner syndrome. They occur most commonly in the mandible (jawbone) but may also grow in the skull and long bones.
- Dental abnormalities – as well as osteomas in the jaw there may be other dental abnormalities such as unerupted extra teeth and caries
- Multifocal pigmented lesions of the fundus in the eye – seen in 80% of patients. These lesions may be present shortly after birth and can be the first marker of the disease.
Who Is at Risk for Gardner’s Syndrome?
The main risk factor for developing Gardner’s syndrome is having at least one parent with the condition.
What Are the Symptoms of Gardner’s Syndrome?
The main symptom of Gardner’s syndrome is multiple growths in the colon. The growths are also known as polyps. Although the number of growths varies, they can be in the hundreds.
In addition to growths on the colon, extra teeth can develop, along with bony tumors on the skull. Another common symptom of Gardner’s syndrome is cysts, which can form under the skin on various parts of the body.
Fibromas and epithelial cysts are common. People with the syndrome also have a higher risk of developing colon cancer.
How is Gardner syndrome diagnosed?
Radiological studies are essential for patients and family members with suspected Gardner syndrome.
- Images of the long bone may show up osteomas.
- Images of the mandible at an early age may show up subtle defects.
- Eye exams at an early age can detect pigmented lesions of the fundus.
- Colonoscopy and other invasive tests to check for polyp involvement every 1-2 years.
What is the treatment for Gardner syndrome?
Treatment of epidermoid cysts in Gardner syndrome is similar to that used for ordinary cysts and involves excision. Occasionally intralesional steroid injections may be used if the cysts are inflamed.
Surgical removal of gastrointestinal polyps is recommended because of the very high risk of polyps developing into cancer. Patients need regular colonoscopies.
Osteomas may also require excision only if they are severely deforming or if they are a nuisance.
What Is the Outlook for Gardner’s Syndrome?
The prognosis for people with Gardner’s syndrome varies, depending on the severity of symptoms. According to Stanford Medicine, people who have an APC gene mutation such as Gardner’s syndrome have an increasingly high chance of developing colon cancer as they age.
Without surgical treatment, almost all people with the APC gene mutation will develop colon cancer by age 40.
How Is Gardner’s Syndrome Prevented?
Since the condition is inherited, there is no way to prevent it. Genetic testing is possible to determine if a person carries the gene mutation.